$ 16^{-\frac{1}{4}}$
$= \left(\dfrac{1}{16}\right)^{\frac{1}{4}}$ Figure out what goes in the blank: $\Big(? \Big)^{4}=\dfrac{1}{16}$ Figure out what goes in the blank: $\Big({\dfrac{1}{2}}\Big)^{4}=\dfrac{1}{16}$ So $16^{-\frac{1}{4}}=\left(\dfrac{1}{16}\right)^{\frac{1}{4}}=\dfrac{1}{2}$